A recent spate of insider acquisitions may be motivated by strong earnings and market returns. But some experts say the buying is less than bullish.

Insider Tables: Buyers | SellersAS THE SUMMER SIZZLES, insiders have started buying again lately.Sentiment apparently improved during the week ended July 28 as insiders boosted their open-market purchases 32% from the prior week, according to Thomson Financial. Some of the top insider buys last week were of XTO Energy, eBay and RadioShack stock, according to Thomson.That suggests a pick-up from the tepid rate of insider buying during the entire month of July. Last month's average buying was lower than the average of this year's first six months, as well as 2004's first seven months.Meanwhile, during the week ending July...